What version of windows are you using? *I assume it is windows*
Or go to Microsoft.com and look up how to do factory reset of your version of windows..

*I would first read on Micorsoft about finding & checking your wifi settings, before re setting the whole system.. Maybe something just got scrambled or turned off...
Microsoft.com - Google Search


*Or reboot the computer to see if it fixes itself first?

If any of the * easier ideas work and you don't have to factory reset it, I do suggest a cleaner/maint utility to tidy up excess files and bad files..

I used this one when I had windows..easy to use one step cleaning, but you can use the advanced settings if you want..
Glary Utilities - Free System Utilities to Clean Registry, Fix PC Errors, Protect Privacy | Glarysoft
or some other well rated free options-
CCleaner, Recuva, Defraggler & Speccy - All Products - Piriform


How to refresh, reset, or restore your PC
How to refresh, reset, or restore your PC - Windows Help

Or Dell has this info-
How to restore your Windows 7 computer to factory settings | Dell US
other Windows versions info-
http://www.dell.com/support/contents...rating-Systems


After the factory reset, if it still does not connect to wifi, do you have a network cable that you can plug in connect to the router or modem temporarily?
Sometimes if plugged in then you can go online to find the drivers needed, but if factory reset you will have to also get all the system updates again from Microsoft.
and whatever your anti virus is you'll have to get that installed set up again..


Be sure to only allow remote hosting connections to well known trusted websites, there are some spoofed sites that look very similar to the real legit ones..